Genetic of milk flow in Alpine and Saanen goats

Abstract

The first minute of milk flow of goats varies between 0.3 and 2.4 kg. Observation of half sib families in the Moissac progeny-test station during 8 years (1585 lactations of 893 goats born from 97 sires and 487 dams) showed 3 types of sires, suggesting the possible existence of a major gene with 2 segregating alleles, + , normal and partially dominant, and hd, recessive, increasing milk flow. This hypothesis of a mixed inheritance was confirmed using different test statistics. The average milk flow of homozygous hd/hd goats is 84 % higher than the +/+ mean (1.48 vs 0.80 kg/min, respectively), the value of heterozygous hd/+ averaging 0.94 kg/min, i.e. a 0.61 dominance ratio. In the studied sample, the allele hd frequency was 0.39 and the marginal heritability 0.48. We conclude that selecting goats with high milk flow is possible and useful. This selection may be organized within the sire dams sub-population (considering the best indexes in protein production and protein content), in order to detect dams with a milk flow higher than 1.46 kg/min (supposed hd/hd) and which rapidly produce young males having a large probability of being hd/hd.